The Influence of Rootstock on Fruit Ethylene, Respiration, Index of Absorbance Difference, Fruit Quality, and Production of ‘Aztec Fuji’ Apple under a Full-crop Condition

Abstract

Selection of dwarfing rootstocks that facilitate optimum production of high-quality fruit is crucial in modern high-density apple orchards. In addition to tree growth and yield, rootstocks can influence fruit maturity of scion cultivars in apples. In this study, the impact of 17 rootstocks on fruit maturity, yield, and quality attributes of ‘Aztec Fuji’ apples (Malus domestica Borkh.) at harvest were evaluated in a season when all trees were in a “full-crop” condition. Keeping sealed fruit at room temperature, a typical climacteric pattern was observed in ethylene evolution, respiration, and oxygen consumption, peaking after 5–7 days in fruit from trees on all rootstocks. During the ripening period, ethylene evolution and respiration rates in fruit from trees on Supp.3, G.3001, and G.202 were often in the high-range category, whereas those on CG.4004, CG.4214, G.41N, and B.9 were in the midrange category and those on M.9Pajam2, M.26EMLA, and G.11 were in the low-range category. Evolved ethylene and respiration in fruit from trees on M9.T337 steadily and slowly increased from 7 days after harvest (7DAH) to 13 days after which harvest (13DAH) ethylene sharply increased, signaling occurrence of climacteric peak, while respiration declined after the peak of 13DAH. In fruit from trees on most rootstocks, the rates of oxygen consumption had inverse relationships with the rates of respiration, so that fruit from trees on M9.T337 had higher and those on G.41N and Supp.3 had lower rates of oxygen consumption. Trees on G.41N, CG.4004, and M.26EMLA had higher and those on CG.4003 had lower yield per tree than trees on other rootstocks. Trees on B.9 and M.9T337 were most yield efficient among trees on all rootstocks. Trees on CG.4004 had larger fruits than those on other rootstocks. Considering all fruit maturity, quality, and yield attributes, CG.4004 seems to be a good choice of rootstock for ‘Aztec Fuji’ under the conditions of this study.